This invention relates to a unit for use in a measuring device such as a vibration rod transducer or other device.
A vibration rod transducer is a device which is used for measuring pressure, flow rate and other like parameters. The apparatus includes an elastic support, typically in the form of a ring, which is subjected to a load under measurement, a bridging strip across the support, an electromagnetic unit on one side of the strip and an electromagnetic generator on the other side of the strip. When the strip is made of a metal and starts to vibrate, an EMF is generated in the electromagnetic unit, the frequency of which is equal to the frequency of oscillation of the strip. The signal from the electromagnetic unit is transmitted to an amplifier, the output of which is coupled to the generator. The frequency of oscillation is dependent on the pressure, flow, or other like parameter in which the transducer is placed.
One known method of producing diamond layers on a substrate is chemical vapour deposition (CVD). CVD involves the synthesis of diamonds from the gas phase. The process generally involves providing a mixture of hydrogen or oxygen gas and a suitable gaseous carbon compound such as a hydrocarbon, applying sufficient energy to that gas to dissociate the hydrogen or oxygen into atomic hydrogen or oxygen and a gas into active carbon ions, atoms or CH radicals and allowing such active species to deposit on a substrate to form diamond. Dissociation of the gases can take place by a variety of methods.
One such method is the use of a hot filament. In this method, the gas temperature at the filament is about 2000.degree. C. and the temperature of the substrate on which diamond growth occurs is about 800.degree. to 1100.degree. C.
A second commonly used method of dissociation is a plasma assisted method. The hydrogen or oxygen and gaseous carbon compound are excited into a reactive state in a plasma region. The energy of excitation may be microwave, RF or DC plasma, UV light or heat. The substrate is heated by the plasma.